Server Load Balancer (SLB) can help protect from distributed denial-of-service (DDoS) attacks by distributing network traffic across groups of backend servers to improve the service capability and application availability. SLB also supports built-in Anti-DDoS services to ensure business security.Anti-DDoS services can mitigate DDoS attacks at the Tbit/s level and provide multiple defense methods, such as blackhole filtering, traffic scrubbing, and access control1.In addition, you can integrate Application Load Balancer (ALB) with Web Application Firewall (WAF) in the console to ensure security at the application layer and prevent attacks such as SQL injection2.Reference:1:Server Load Balancer(SLB) - Alibaba Cloud2:Associate an EIP protected by Anti-DDoS Pro/Premium with an ALB instance - Server Load Balancer - Alibaba Cloud Documentation Center.

Object Storage Service (OSS) is a cloud storage service that provides secure, cost-effective, and scalable storage for various data types, such as images, videos, and documents. OSS can store large amounts of data and support concurrent access from multiple users. OSS can also integrate with other Alibaba Cloud services, such as Media Transcoding Service (MTS), Server Load Balancer (SLB), and Elastic Compute Service (ECS). By using OSS, the portal can offload the storage and delivery of the image content from the ECS instance, which can improve the performance and availability of the application.

Content Delivery Network (CDN) is a distributed network that delivers content to users based on their geographic locations, the origin servers, and the content delivery policies. CDN can accelerate the delivery of static and dynamic content, such as images, videos, and web pages, by caching the content at edge nodes that are closer to the users. CDN can also reduce the network latency and bandwidth consumption, as well as enhance the security and reliability of the content delivery. By using CDN, the portal can speed up the loading of images and improve the user experience.

Therefore, the combination of OSS and CDN can help resolve the storage and performance issue of the portal at the same time. The other combinations are not as effective or suitable for the portal's scenario. OSS + MTS combination can help with the storage and transcoding of media files, but not with the delivery of images. OSS + RDS combination can help with the storage and management of relational databases, but not with the loading of images. OSS + ECS combination can help with the storage and computing of data, but not with the acceleration of content delivery.

Alibaba Cloud Object Storage Service

Alibaba Cloud Content Delivery Network

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The issue that Company B faces is that their music files stored in OSS are being downloaded by unauthorized users who access them through search engines, rather than through their website. This is called leeching, which is a form of bandwidth theft that consumes the OSS traffic and increases the cost for Company B. To address this issue, Company B can limit the access sources by configuring the ''Anti-leech settings'' of OSS bucket attributes. Anti-leech settings allow the bucket owner to specify a referer whitelist, which is a list of domain names that are allowed to access the OSS resources. The referer is a part of the HTTP header that indicates the source URL of the request. By setting a referer whitelist, Company B can prevent leeches from accessing their music files directly from search engines or other websites, and only allow access from their own website domain name. This way, Company B can protect their OSS resources from unauthorized access and reduce their OSS traffic costs. The other options are not effective or relevant for addressing the issue. Migrating music files from OSS to data disks for ECS instances would increase the storage and computing costs for Company B, and also reduce the scalability and availability of their music files. Changing the website access mode to HTTPS would enhance the security and encryption of the website, but it would not prevent leeches from accessing the OSS resources through search engines. Introducing SLB for extra protection would improve the load balancing and high availability of the ECS instances, but it would not affect the access control of the OSS resources.Reference:OSS Anti-Leech Referer Configuration and Error Elimination

ApsaraDB RDS for MySQL is a cloud-based relational database service that provides secure, cost-effective, and scalable database solutions for various applications. RDS for MySQL supports creating read-only instances that are synchronized with the primary instance in real time. Read-only instances can handle read requests from applications and reduce the read pressure on the primary instance. This can improve the performance and availability of the database system. Read-only instances can also be used for scenarios such as report analysis, data backup, and disaster recovery.

Overview of read-only ApsaraDB RDS for MySQL instances

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Alibaba Cloud Computing Exam Question 2022

Alibaba Cloud Server Load Balancer (SLB) is a service that distributes network traffic across multiple ECS instances to improve the service capabilities of applications. SLB supports the following protocols for the listener configuration:

HTTP: Hypertext Transfer Protocol, a stateless application-layer protocol that is used to transfer web pages and other resources over the internet.

HTTPS: Hypertext Transfer Protocol Secure, an extension of HTTP that uses SSL/TLS encryption to provide secure communication between the client and the server.

TCP: Transmission Control Protocol, a reliable, connection-oriented transport-layer protocol that provides reliable data delivery and error recovery.

UDP: User Datagram Protocol, a connectionless transport-layer protocol that provides fast and efficient data transmission without guaranteeing reliability or order.

SLB does not support the following protocols:

MPLS: Multiprotocol Label Switching, a data-carrying technique that uses labels to forward packets across a network.

MQTT: Message Queuing Telemetry Transport, a lightweight publish/subscribe messaging protocol that is designed for constrained devices and low-bandwidth networks.

Alibaba Cloud Server Load Balancer

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Alibaba Cloud Computing Exam Question 2022